Under pathological conditions in the middle ear, such as secretory otitis media (SOM), muco-exudates produced by the muco-ciliary system may accumulate instead of clear through the eustachian tube. In earlier research we have established that for proper clearance by ciliary action mucus must have the character of an incipient gel and that it is normally secreted as such. Mucus, however, undergoes spontaneous structural changes since it is not normally a permanently cross-linked system. It has also been shown that the muco-ciliary system of the eustachian tube in SOM ears is functional. Hence the effectiveness of clearance can be linked to the number of cells producing mucus, the amount produced and the rheological character of the secretion. The objectives of this project are to characterize the features of the glycoprotein macromolecular aggregates from which mucus derives its special rheological properties and determine the factors linking molecular structure, rheological response and transportability on the epithelium. We wish to determine in particular the structure of the glycoprotein entity, the distribution of cross-links, the mechanics of ciliary beat and factors controlling mucus production.